Such inserts are generally of the replaceable kind and are designed to be firmly held in an appropriate receiving seat formed in an insert holder. Thus, for example, the insert can be formed with a tapering, wedge-shaped body so as to be wedge clamped within a correspondingly wedge-shaped slot formed in the insert holder. Alternatively, the insert can be clamped between a pair of jaws of the insert holder, which jaws define a receiving slot, the jaws being biased into clamping the insert by suitable mechanical means.
Seeing that the metal cutting operations involve the removal (from the workpiece being cut) of metal, in the form of chips, the interests of safety and efficiency of cutting require that these chips be effectively removed from the cutting region. To this end it has long been known to provide such cutting inserts with chip breaking and/or forming means so as to ensure that the chips, shortly after their formation, are so shaped and/or broken that they can be readily removed from the work area without interfering with the continuing cutting process and without endangering the operating personnel.
In the use of such cutting inserts for the purposes indicated, it has long been known to draw a distinction between tools for parting or grooving operations, on the one hand, and tools for lateral turning (e.g. cylindrical) operations, on the other hand. In the first instance, there is a radial movement of the tool into the rotating workpiece to be grooved or parted whilst, in the second instance, there is a lateral or transverse movement of the tool. When carrying out these differing kinds of operations, it has long been known that it is necessary to replace the holder and the cutting insert when passing from one operation to the other, seeing that the cutting insert employed for any particular operation is designed so as to meet only the requirements of that operation.
This necessity to replace the cutting insert in accordance with the nature of the cutting operation is clearly time-consuming and requires the ready availability of differing kinds of operations. In the light of this existing situation, the applicants have developed a new tool cutting system known by the applicants' trademark CUT-GRIP, wherein the same cutting insert can be used for both parting and grooving operations, on the one hand, and also for lateral turning operations, on the other hand. Such an insert will hereinafter be referred to as a "multidirectional cutting tool insert".
Such multidirectional cutting tool inserts are adapted to be held by specially designed tool holders having a pair of gripping jaws formed integral therewith and with each other, the gripping jaws defining between them a receiving slot within which the insert is to be clamped, this receiving slot communicating with an elongated slit formed in the holder and extending longitudinally therein away from the slot. A screw clamping means extends through the tool holder in the region of the slit so that, upon insertion of the insert into the slot, tightening of the screw clamping means results in the uppermost jaw being biased into a tight clamping relationship with the upper surface of the insert. Preferably, the adjacent surfaces of the insert and the jaws are formed with mating keying surfaces to as to ensure the correct alignment of the insert and so as to prevent its lateral displacement once it is clamped in the tool holder.
Hitherto, in order to clamp multidirectional inserts of this kind with the inserts being directed at acute angles with respect to the longitudinal axes of the tool holders, it was necessary for the lowermost jaws of the tool holders to define acute angles at their outermost corners. Seeing that the tool holder and especially the outermost corners thereof have to be capable of withstanding considerable forces during operation, it will be readily appreciated that the fact that the outermost corner defines an acute angle, of necessity implies that the corner is relatively weak and can be subjected to breakage under stress.